/*
 * Copyright MITRE
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.foreveross.common.proxy;

import org.apache.http.*;
import org.apache.http.client.HttpClient;
import org.apache.http.client.config.CookieSpecs;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.AbortableHttpRequest;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.entity.InputStreamEntity;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.message.BasicHeader;
import org.apache.http.message.BasicHttpEntityEnclosingRequest;
import org.apache.http.message.BasicHttpRequest;
import org.apache.http.message.HeaderGroup;
import org.apache.http.util.EntityUtils;
import org.iff.infra.util.PreCheckHelper;
import org.iff.infra.util.StreamHelper;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.Closeable;
import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpCookie;
import java.net.URI;
import java.util.BitSet;
import java.util.Enumeration;
import java.util.Formatter;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * An HTTP reverse proxy/gateway servlet. It is designed to be extended for customization
 * if desired. Most of the work is handled by
 * <a href="http://hc.apache.org/httpcomponents-client-ga/">Apache HttpClient</a>.
 * <p>
 * There are alternatives to a servlet based proxy such as Apache mod_proxy if that is available to you. However
 * this servlet is easily customizable by Java, secure-able by your web application's security (e.g. spring-security),
 * portable across servlet engines, and is embeddable into another web application.
 * </p>
 * <p>
 * Inspiration: http://httpd.apache.org/docs/2.0/mod/mod_proxy.html
 * </p>
 *
 * @author David Smiley dsmiley@apache.org
 */
@SuppressWarnings({"deprecation", "serial"})
public class ProxyServlet implements Closeable {

    /**
     * A boolean parameter name to enable logging of input and target URLs to the servlet log.
     */
    public static final String P_LOG = "log";

    /* INIT PARAMETER NAME CONSTANTS */
    /**
     * A boolean parameter name to enable forwarding of the client IP
     */
    public static final String P_FORWARDEDFOR = "forwardip";
    /**
     * A boolean parameter name to keep HOST parameter as-is
     */
    public static final String P_PRESERVEHOST = "preserveHost";
    /**
     * A boolean parameter name to keep COOKIES as-is
     */
    public static final String P_PRESERVECOOKIES = "preserveCookies";
    /**
     * A boolean parameter name to have auto-handle redirects
     */
    public static final String P_HANDLEREDIRECTS = "http.protocol.handle-redirects"; // ClientPNames.HANDLE_REDIRECTS
    /**
     * A integer parameter name to set the socket connection timeout (millis)
     */
    public static final String P_CONNECTTIMEOUT = "http.socket.timeout"; // CoreConnectionPNames.SO_TIMEOUT
    /**
     * A integer parameter name to set the socket read timeout (millis)
     */
    public static final String P_READTIMEOUT = "http.read.timeout";
    /**
     * A boolean parameter whether to use JVM-defined system properties to configure various networking aspects.
     */
    public static final String P_USESYSTEMPROPERTIES = "useSystemProperties";
    /**
     * The parameter name for the target (destination) URI to proxy to.
     */
    public static final String P_TARGET_URI = "targetUri";
    public static final String ATTR_TARGET_URI =
            ProxyServlet.class.getSimpleName() + ".targetUri";
    public static final String ATTR_TARGET_HOST =
            ProxyServlet.class.getSimpleName() + ".targetHost";
    /**
     * These are the "hop-by-hop" headers that should not be copied.
     * http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html
     * I use an HttpClient HeaderGroup class instead of Set&lt;String&gt; because this
     * approach does case insensitive lookup faster.
     */
    protected static final HeaderGroup hopByHopHeaders;

    /* MISC */
    protected static final BitSet asciiQueryChars;
    /**
     * 改造
     */
    private static final org.iff.infra.util.Logger.Log Logger = org.iff.infra.util.Logger.get("FOSS.SHIRO");
    /**
     * 改造
     */
    private static final Pattern linkPattern = Pattern.compile("\\b(href=|src=|action=|url\\()([\"\'])(([^/]+://)([^/<>]+))?([^\"\'>]*)[\"\']", Pattern.CASE_INSENSITIVE | Pattern.CANON_EQ);
    /**
     * 改造
     */
    private static HttpClient proxyClient;

    static {
        hopByHopHeaders = new HeaderGroup();
        String[] headers = new String[]{
                "Connection", "Keep-Alive", "Proxy-Authenticate", "Proxy-Authorization",
                "TE", "Trailers", "Transfer-Encoding", "Upgrade"};
        for (String header : headers) {
            hopByHopHeaders.addHeader(new BasicHeader(header, null));
        }
    }

    static {
        char[] c_unreserved = "_-!.~'()*".toCharArray();//plus alphanum
        char[] c_punct = ",;:$&+=".toCharArray();
        char[] c_reserved = "?/[]@".toCharArray();//plus punct

        asciiQueryChars = new BitSet(128);
        for (char c = 'a'; c <= 'z'; c++) asciiQueryChars.set((int) c);
        for (char c = 'A'; c <= 'Z'; c++) asciiQueryChars.set((int) c);
        for (char c = '0'; c <= '9'; c++) asciiQueryChars.set((int) c);
        for (char c : c_unreserved) asciiQueryChars.set((int) c);
        for (char c : c_punct) asciiQueryChars.set((int) c);
        for (char c : c_reserved) asciiQueryChars.set((int) c);

        asciiQueryChars.set((int) '%');//leave existing percent escapes in place
    }

    protected boolean doLog = false;
    protected boolean doForwardIP = true;
    /**
     * User agents shouldn't send the url fragment but what if it does?
     */
    protected boolean doSendUrlFragment = true;
    protected boolean doPreserveHost = false;
    protected boolean doPreserveCookies = false;
    //These next 3 are cached here, and should only be referred to in initialization logic. See the
    // ATTR_* parameters.
    protected boolean doHandleRedirects = false;
    protected boolean useSystemProperties = false;
    protected int connectTimeout = -1;
    protected int readTimeout = -1;
    /**
     * From the configured parameter "targetUri".
     */
    protected String targetUri;
    protected URI targetUriObj;//new URI(targetUri)
    protected HttpHost targetHost;//URIUtils.extractHost(targetUriObj);
    /**
     * 改造
     */
    protected Map<String, String> config;
    protected Map<String, String> customHeader;

    /**
     * 改造
     */
    public ProxyServlet(Map<String, String> config) {
        this.config = PreCheckHelper.checkNotEmpty(config);
        try {
            init();
        } catch (ServletException e) {
            e.printStackTrace();
        }
    }

    /**
     * 改造
     */
    public ProxyServlet(Map<String, String> config, Map<String, String> customHeader) {
        this.config = PreCheckHelper.checkNotEmpty(config);
        this.customHeader = customHeader;
        try {
            init();
        } catch (ServletException e) {
            e.printStackTrace();
        }
    }

    /**
     * Encodes characters in the query or fragment part of the URI.
     *
     * <p>Unfortunately, an incoming URI sometimes has characters disallowed by the spec.  HttpClient
     * insists that the outgoing proxied request has a valid URI because it uses Java's {@link URI}.
     * To be more forgiving, we must escape the problematic characters.  See the URI class for the
     * spec.
     *
     * @param in            example: name=value&amp;foo=bar#fragment
     * @param encodePercent determine whether percent characters need to be encoded
     */
    protected static CharSequence encodeUriQuery(CharSequence in, boolean encodePercent) {
        //Note that I can't simply use URI.java to encode because it will escape pre-existing escaped things.
        StringBuilder outBuf = null;
        Formatter formatter = null;
        for (int i = 0; i < in.length(); i++) {
            char c = in.charAt(i);
            boolean escape = true;
            if (c < 128) {
                if (asciiQueryChars.get((int) c) && !(encodePercent && c == '%')) {
                    escape = false;
                }
            } else if (!Character.isISOControl(c) && !Character.isSpaceChar(c)) {//not-ascii
                escape = false;
            }
            if (!escape) {
                if (outBuf != null)
                    outBuf.append(c);
            } else {
                //escape
                if (outBuf == null) {
                    outBuf = new StringBuilder(in.length() + 5 * 3);
                    outBuf.append(in, 0, i);
                    formatter = new Formatter(outBuf);
                }
                //leading %, 0 padded, width 2, capital hex
                formatter.format("%%%02X", (int) c);//TODO
            }
        }
        return outBuf != null ? outBuf : in;
    }

    /**
     * 改造
     */
    void log(String msg, Throwable e) {
        Logger.info(msg, e);
    }

    /**
     * 改造
     */
    void log(String msg) {
        Logger.info(msg);
    }

    //改造@Override
    public String getServletInfo() {
        return "A proxy servlet by David Smiley, dsmiley@apache.org";
    }

    protected String getTargetUri(HttpServletRequest servletRequest) {
        return (String) servletRequest.getAttribute(ATTR_TARGET_URI);
    }

    protected HttpHost getTargetHost(HttpServletRequest servletRequest) {
        return (HttpHost) servletRequest.getAttribute(ATTR_TARGET_HOST);
    }

    /**
     * Reads a configuration parameter. By default it reads servlet init parameters but
     * it can be overridden.
     */
    protected String getConfigParam(String key) {
        return config.get(key);//改造
    }

    //改造@Override
    public void init() throws ServletException {
        String doLogStr = getConfigParam(P_LOG);
        if (doLogStr != null) {
            this.doLog = Boolean.parseBoolean(doLogStr);
        }

        String doForwardIPString = getConfigParam(P_FORWARDEDFOR);
        if (doForwardIPString != null) {
            this.doForwardIP = Boolean.parseBoolean(doForwardIPString);
        }

        String preserveHostString = getConfigParam(P_PRESERVEHOST);
        if (preserveHostString != null) {
            this.doPreserveHost = Boolean.parseBoolean(preserveHostString);
        }

        String preserveCookiesString = getConfigParam(P_PRESERVECOOKIES);
        if (preserveCookiesString != null) {
            this.doPreserveCookies = Boolean.parseBoolean(preserveCookiesString);
        }

        String handleRedirectsString = getConfigParam(P_HANDLEREDIRECTS);
        if (handleRedirectsString != null) {
            this.doHandleRedirects = Boolean.parseBoolean(handleRedirectsString);
        }

        String connectTimeoutString = getConfigParam(P_CONNECTTIMEOUT);
        if (connectTimeoutString != null) {
            this.connectTimeout = Integer.parseInt(connectTimeoutString);
        }

        String readTimeoutString = getConfigParam(P_READTIMEOUT);
        if (readTimeoutString != null) {
            this.readTimeout = Integer.parseInt(readTimeoutString);
        }

        String useSystemPropertiesString = getConfigParam(P_USESYSTEMPROPERTIES);
        if (useSystemPropertiesString != null) {
            this.useSystemProperties = Boolean.parseBoolean(useSystemPropertiesString);
        }

        initTarget();//sets target*

        if (proxyClient == null) {
            proxyClient = createHttpClient(buildRequestConfig());
        }
    }

    /**
     * Sub-classes can override specific behaviour of {@link RequestConfig}.
     */
    protected RequestConfig buildRequestConfig() {
        return RequestConfig.custom()
                .setRedirectsEnabled(doHandleRedirects)
                .setCookieSpec(CookieSpecs.IGNORE_COOKIES) // we handle them in the servlet instead
                .setConnectTimeout(connectTimeout)
                .setSocketTimeout(readTimeout)
                .build();
    }

    protected void initTarget() throws ServletException {
        targetUri = getConfigParam(P_TARGET_URI);
        if (targetUri == null)
            throw new ServletException(P_TARGET_URI + " is required.");
        //test it's valid
        try {
            targetUriObj = new URI(targetUri);
        } catch (Exception e) {
            throw new ServletException("Trying to process targetUri init parameter: " + e, e);
        }
        targetHost = URIUtils.extractHost(targetUriObj);
    }

    /**
     * Called from {@link # init(javax.servlet.ServletConfig)}.
     * HttpClient offers many opportunities for customization.
     * In any case, it should be thread-safe.
     */
    protected HttpClient createHttpClient(final RequestConfig requestConfig) {
        HttpClientBuilder clientBuilder = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig);
        if (useSystemProperties) {
            clientBuilder = clientBuilder.useSystemProperties();
        }
        return clientBuilder.build();
    }

    /**
     * The http client used.
     *
     * @see #createHttpClient(RequestConfig)
     */
    protected HttpClient getProxyClient() {
        return proxyClient;
    }

    //改造@Override
    public void destroy() {
        //Usually, clients implement Closeable:
        if (proxyClient instanceof Closeable) {
            try {
                ((Closeable) proxyClient).close();
            } catch (IOException e) {
                log("While destroying servlet, shutting down HttpClient: " + e, e);
            }
        } else {
            //Older releases require we do this:
            if (proxyClient != null) {
                proxyClient.getConnectionManager().shutdown();
            }
        }
        //改造super.destroy();
    }

    //@Override
    public void service(HttpServletRequest servletRequest, HttpServletResponse servletResponse)
            throws ServletException, IOException {
        //initialize request attributes from caches if unset by a subclass by this point
        if (servletRequest.getAttribute(ATTR_TARGET_URI) == null) {
            servletRequest.setAttribute(ATTR_TARGET_URI, targetUri);
        }
        if (servletRequest.getAttribute(ATTR_TARGET_HOST) == null) {
            servletRequest.setAttribute(ATTR_TARGET_HOST, targetHost);
        }

        // Make the Request
        //note: we won't transfer the protocol version because I'm not sure it would truly be compatible
        String method = servletRequest.getMethod();
        String proxyRequestUri = rewriteUrlFromRequest(servletRequest);
        HttpRequest proxyRequest;
        //spec: RFC 2616, sec 4.3: either of these two headers signal that there is a message body.
        if (servletRequest.getHeader(HttpHeaders.CONTENT_LENGTH) != null ||
                servletRequest.getHeader(HttpHeaders.TRANSFER_ENCODING) != null) {
            proxyRequest = newProxyRequestWithEntity(method, proxyRequestUri, servletRequest);
        } else {
            proxyRequest = new BasicHttpRequest(method, proxyRequestUri);
        }

        copyRequestHeaders(servletRequest, proxyRequest);

        setXForwardedForHeader(servletRequest, proxyRequest);

        HttpResponse proxyResponse = null;
        try {
            // Execute the request
            proxyResponse = doExecute(servletRequest, servletResponse, proxyRequest);

            // Process the response:

            // Pass the response code. This method with the "reason phrase" is deprecated but it's the
            //   only way to pass the reason along too.
            int statusCode = proxyResponse.getStatusLine().getStatusCode();
            //noinspection deprecation
            servletResponse.setStatus(statusCode, proxyResponse.getStatusLine().getReasonPhrase());

            // Copying response headers to make sure SESSIONID or other Cookie which comes from the remote
            // server will be saved in client when the proxied url was redirected to another one.
            // See issue [#51](https://github.com/mitre/HTTP-Proxy-Servlet/issues/51)
            copyResponseHeaders(proxyResponse, servletRequest, servletResponse);

            if (statusCode == HttpServletResponse.SC_NOT_MODIFIED) {
                // 304 needs special handling.  See:
                // http://www.ics.uci.edu/pub/ietf/http/rfc1945.html#Code304
                // Don't send body entity/content!
                servletResponse.setIntHeader(HttpHeaders.CONTENT_LENGTH, 0);
            } else {
                // Send the content to the client
                copyResponseEntity(proxyResponse, servletResponse, proxyRequest, servletRequest);
            }

        } catch (Exception e) {
            handleRequestException(proxyRequest, e);
        } finally {
            // make sure the entire entity was consumed, so the connection is released
            if (proxyResponse != null)
                EntityUtils.consumeQuietly(proxyResponse.getEntity());
            //Note: Don't need to close servlet outputStream:
            // http://stackoverflow.com/questions/1159168/should-one-call-close-on-httpservletresponse-getoutputstream-getwriter
        }
    }

    protected void handleRequestException(HttpRequest proxyRequest, Exception e) throws ServletException, IOException {
        //abort request, according to best practice with HttpClient
        if (proxyRequest instanceof AbortableHttpRequest) {
            AbortableHttpRequest abortableHttpRequest = (AbortableHttpRequest) proxyRequest;
            abortableHttpRequest.abort();
        }
        if (e instanceof RuntimeException)
            throw (RuntimeException) e;
        if (e instanceof ServletException)
            throw (ServletException) e;
        //noinspection ConstantConditions
        if (e instanceof IOException)
            throw (IOException) e;
        throw new RuntimeException(e);
    }

    protected HttpResponse doExecute(HttpServletRequest servletRequest, HttpServletResponse servletResponse,
                                     HttpRequest proxyRequest) throws IOException {
        if (doLog) {
            log("proxy " + servletRequest.getMethod() + " uri: " + servletRequest.getRequestURI() + " -- " +
                    proxyRequest.getRequestLine().getUri());
        }
        return proxyClient.execute(getTargetHost(servletRequest), proxyRequest);
    }

    protected HttpRequest newProxyRequestWithEntity(String method, String proxyRequestUri,
                                                    HttpServletRequest servletRequest)
            throws IOException {
        HttpEntityEnclosingRequest eProxyRequest =
                new BasicHttpEntityEnclosingRequest(method, proxyRequestUri);
        // Add the input entity (streamed)
        //  note: we don't bother ensuring we close the servletInputStream since the container handles it
        eProxyRequest.setEntity(
                new InputStreamEntity(servletRequest.getInputStream(), getContentLength(servletRequest)));
        return eProxyRequest;
    }

    // Get the header value as a long in order to more correctly proxy very large requests
    private long getContentLength(HttpServletRequest request) {
        String contentLengthHeader = request.getHeader("Content-Length");
        if (contentLengthHeader != null) {
            return Long.parseLong(contentLengthHeader);
        }
        return -1L;
    }

    protected void closeQuietly(Closeable closeable) {
        try {
            closeable.close();
        } catch (IOException e) {
            log(e.getMessage(), e);
        }
    }

    /**
     * Copy request headers from the servlet client to the proxy request.
     * This is easily overridden to add your own.
     */
    protected void copyRequestHeaders(HttpServletRequest servletRequest, HttpRequest proxyRequest) {
        // Get an Enumeration of all of the header names sent by the client
        @SuppressWarnings("unchecked")
        Enumeration<String> enumerationOfHeaderNames = servletRequest.getHeaderNames();
        while (enumerationOfHeaderNames.hasMoreElements()) {
            String headerName = enumerationOfHeaderNames.nextElement();
            copyRequestHeader(servletRequest, proxyRequest, headerName);
        }

        /**
         * 改造
         */
        if (customHeader != null) {
            for (Map.Entry<String, String> entry : customHeader.entrySet()) {
                proxyRequest.addHeader(entry.getKey(), entry.getValue());
            }
        }
    }

    /**
     * Copy a request header from the servlet client to the proxy request.
     * This is easily overridden to filter out certain headers if desired.
     */
    protected void copyRequestHeader(HttpServletRequest servletRequest, HttpRequest proxyRequest,
                                     String headerName) {
        //Instead the content-length is effectively set via InputStreamEntity
        if (headerName.equalsIgnoreCase(HttpHeaders.CONTENT_LENGTH))
            return;
        if (hopByHopHeaders.containsHeader(headerName))
            return;

        @SuppressWarnings("unchecked")
        Enumeration<String> headers = servletRequest.getHeaders(headerName);
        while (headers.hasMoreElements()) {//sometimes more than one value
            String headerValue = headers.nextElement();
            // In case the proxy host is running multiple virtual servers,
            // rewrite the Host header to ensure that we get content from
            // the correct virtual server
            if (!doPreserveHost && headerName.equalsIgnoreCase(HttpHeaders.HOST)) {
                HttpHost host = getTargetHost(servletRequest);
                headerValue = host.getHostName();
                if (host.getPort() != -1)
                    headerValue += ":" + host.getPort();
            } else if (!doPreserveCookies && headerName.equalsIgnoreCase(org.apache.http.cookie.SM.COOKIE)) {
                headerValue = getRealCookie(headerValue);
            }
            proxyRequest.addHeader(headerName, headerValue);
        }
    }

    private void setXForwardedForHeader(HttpServletRequest servletRequest,
                                        HttpRequest proxyRequest) {
        if (doForwardIP) {
            String forHeaderName = "X-Forwarded-For";
            String forHeader = servletRequest.getRemoteAddr();
            String existingForHeader = servletRequest.getHeader(forHeaderName);
            if (existingForHeader != null) {
                forHeader = existingForHeader + ", " + forHeader;
            }
            proxyRequest.setHeader(forHeaderName, forHeader);

            String protoHeaderName = "X-Forwarded-Proto";
            String protoHeader = servletRequest.getScheme();
            proxyRequest.setHeader(protoHeaderName, protoHeader);
        }
    }

    /**
     * Copy proxied response headers back to the servlet client.
     */
    protected void copyResponseHeaders(HttpResponse proxyResponse, HttpServletRequest servletRequest,
                                       HttpServletResponse servletResponse) {
        for (Header header : proxyResponse.getAllHeaders()) {
            copyResponseHeader(servletRequest, servletResponse, header);
        }
    }

    /**
     * Copy a proxied response header back to the servlet client.
     * This is easily overwritten to filter out certain headers if desired.
     */
    protected void copyResponseHeader(HttpServletRequest servletRequest,
                                      HttpServletResponse servletResponse, Header header) {
        String headerName = header.getName();
        if (hopByHopHeaders.containsHeader(headerName))
            return;
        String headerValue = header.getValue();
        if (headerName.equalsIgnoreCase(org.apache.http.cookie.SM.SET_COOKIE) ||
                headerName.equalsIgnoreCase(org.apache.http.cookie.SM.SET_COOKIE2)) {
            copyProxyCookie(servletRequest, servletResponse, headerValue);
        } else if (headerName.equalsIgnoreCase(HttpHeaders.LOCATION)) {
            // LOCATION Header may have to be rewritten.
            servletResponse.addHeader(headerName, rewriteUrlFromResponse(servletRequest, headerValue));
        } else {
            servletResponse.addHeader(headerName, headerValue);
        }
    }

    /**
     * Copy cookie from the proxy to the servlet client.
     * Replaces cookie path to local path and renames cookie to avoid collisions.
     */
    protected void copyProxyCookie(HttpServletRequest servletRequest,
                                   HttpServletResponse servletResponse, String headerValue) {
        //build path for resulting cookie
        String path = servletRequest.getContextPath(); // path starts with / or is empty string
        path += servletRequest.getServletPath(); // servlet path starts with / or is empty string
        if (path.isEmpty()) {
            path = "/";
        }

        for (HttpCookie cookie : HttpCookie.parse(headerValue)) {
            //set cookie name prefixed w/ a proxy value so it won't collide w/ other cookies
            String proxyCookieName = doPreserveCookies ? cookie.getName() : getCookieNamePrefix(cookie.getName()) + cookie.getName();
            Cookie servletCookie = new Cookie(proxyCookieName, cookie.getValue());
            servletCookie.setComment(cookie.getComment());
            servletCookie.setMaxAge((int) cookie.getMaxAge());
            servletCookie.setPath(path); //set to the path of the proxy servlet
            // don't set cookie domain
            servletCookie.setSecure(cookie.getSecure());
            servletCookie.setVersion(cookie.getVersion());
            servletResponse.addCookie(servletCookie);
        }
    }

    /**
     * Take any client cookies that were originally from the proxy and prepare them to send to the
     * proxy.  This relies on cookie headers being set correctly according to RFC 6265 Sec 5.4.
     * This also blocks any local cookies from being sent to the proxy.
     */
    protected String getRealCookie(String cookieValue) {
        StringBuilder escapedCookie = new StringBuilder();
        String cookies[] = cookieValue.split("[;,]");
        for (String cookie : cookies) {
            String cookieSplit[] = cookie.split("=");
            if (cookieSplit.length == 2) {
                String cookieName = cookieSplit[0].trim();
                if (cookieName.startsWith(getCookieNamePrefix(cookieName))) {
                    cookieName = cookieName.substring(getCookieNamePrefix(cookieName).length());
                    if (escapedCookie.length() > 0) {
                        escapedCookie.append("; ");
                    }
                    escapedCookie.append(cookieName).append("=").append(cookieSplit[1].trim());
                }
            }
        }
        return escapedCookie.toString();
    }

    /**
     * The string prefixing rewritten cookies.
     */
    protected String getCookieNamePrefix(String name) {

        //改造return "!Proxy!" + getServletConfig().getServletName();
        return "!Proxy!" + config.get("servletName");
    }

    /**
     * Copy response body data (the entity) from the proxy to the servlet client.
     */
    protected void copyResponseEntity(HttpResponse proxyResponse, HttpServletResponse servletResponse,
                                      HttpRequest proxyRequest, HttpServletRequest servletRequest)
            throws IOException {
        HttpEntity entity = proxyResponse.getEntity();
        if (entity != null) {
            OutputStream servletOutputStream = servletResponse.getOutputStream();
            String contentType = servletResponse.getContentType();
            if (contentType == null || contentType.indexOf("html") > -1 || contentType.indexOf("css") > -1) {
                rewriteUrl(servletResponse, servletRequest, entity, (ServletOutputStream) servletOutputStream);

            } else {
                entity.writeTo(servletOutputStream);
            }
        }
    }

    /**
     * 改造
     *
     * @param servletResponse
     * @param servletRequest
     * @param entity
     * @param servletOutputStream
     * @throws IOException
     */
    private void rewriteUrl(HttpServletResponse servletResponse, HttpServletRequest servletRequest, HttpEntity entity, ServletOutputStream servletOutputStream) throws IOException {
        /*
         * Using regex can be quite harsh sometimes so here is how
         * the regex trying to find links works
         *
         * \\b(href=|src=|action=|url\\()([\"\'])
         * This part is the identification of links, matching
         * something like href=", href=' and href=
         *
         * (([^/]+://)([^/<>]+))?
         * This is to identify absolute paths. A link doesn't have
         * to be absolute therefor there is a ?.
         *
         * ([^\"\'>]*)
         * This is the link
         *
         * [\"\']
         * Ending " or '
         *
         * $1 - link type, e.g. href=
         * $2 - ", ' or whitespace
         * $3 - The entire http://www.server.com if present
         * $4 - The protocol, e.g http:// or ftp://
         * $5 - The host name, e.g. www.server.com
         * $6 - The link
         */
        String content = StreamHelper.getContent(entity.getContent(), false);
        StringBuffer page = new StringBuffer();

        Matcher matcher = linkPattern.matcher(content);
        while (matcher.find()) {
            String link = matcher.group(6).replaceAll("\\$", "\\\\\\$");
            if (link.length() == 0) {
                link = "/";
            }
            String rewritten = null;
            if (matcher.group(4) != null) {
                rewritten = matcher.group(6);
            } else {
                if (link.startsWith("/")) {
                    rewritten = matcher.group(1) + matcher.group(2) + servletRequest.getContextPath() + link + matcher.group(2);
                } else if (!link.startsWith(".")) {
                    rewritten = matcher.group(1) + matcher.group(2) + "./" + link + matcher.group(2);
                } else {
                    rewritten = matcher.group(6);
                }
            }
            if (rewritten != null) {
                matcher.appendReplacement(page, rewritten);
            }
        }
        matcher.appendTail(page);
        String pageContent = page.toString();
        byte[] pageBytes = pageContent.getBytes("UTF-8");
        servletResponse.setIntHeader(HttpHeaders.CONTENT_LENGTH, pageBytes.length);
        servletOutputStream.write(pageBytes);
    }

    /**
     * Reads the request URI from {@code servletRequest} and rewrites it, considering targetUri.
     * It's used to make the new request.
     */
    protected String rewriteUrlFromRequest(HttpServletRequest servletRequest) {
        StringBuilder uri = new StringBuilder(500);
        uri.append(getTargetUri(servletRequest));
        // Handle the path given to the servlet
        String pathInfo = servletRequest.getPathInfo();
        if (pathInfo != null) {//ex: /my/path.html
            // getPathInfo() returns decoded string, so we need encodeUriQuery to encode "%" characters
            uri.append(encodeUriQuery(pathInfo, true));
        }
        // Handle the query string & fragment
        String queryString = servletRequest.getQueryString();//ex:(following '?'): name=value&foo=bar#fragment
        String fragment = null;
        //split off fragment from queryString, updating queryString if found
        if (queryString != null) {
            int fragIdx = queryString.indexOf('#');
            if (fragIdx >= 0) {
                fragment = queryString.substring(fragIdx + 1);
                queryString = queryString.substring(0, fragIdx);
            }
        }

        queryString = rewriteQueryStringFromRequest(servletRequest, queryString);
        if (queryString != null && queryString.length() > 0) {
            uri.append('?');
            // queryString is not decoded, so we need encodeUriQuery not to encode "%" characters, to avoid double-encoding
            uri.append(encodeUriQuery(queryString, false));
        }

        if (doSendUrlFragment && fragment != null) {
            uri.append('#');
            // fragment is not decoded, so we need encodeUriQuery not to encode "%" characters, to avoid double-encoding
            uri.append(encodeUriQuery(fragment, false));
        }
        return uri.toString();
    }

    protected String rewriteQueryStringFromRequest(HttpServletRequest servletRequest, String queryString) {
        return queryString;
    }

    /**
     * For a redirect response from the target server, this translates {@code theUrl} to redirect to
     * and translates it to one the original client can use.
     */
    protected String rewriteUrlFromResponse(HttpServletRequest servletRequest, String theUrl) {
        //TODO document example paths
        final String targetUri = getTargetUri(servletRequest);
        if (theUrl.startsWith(targetUri)) {
            /*-
             * The URL points back to the back-end server.
             * Instead of returning it verbatim we replace the target path with our
             * source path in a way that should instruct the original client to
             * request the URL pointed through this Proxy.
             * We do this by taking the current request and rewriting the path part
             * using this servlet's absolute path and the path from the returned URL
             * after the base target URL.
             */
            StringBuffer curUrl = servletRequest.getRequestURL();//no query
            int pos;
            // Skip the protocol part
            if ((pos = curUrl.indexOf("://")) >= 0) {
                // Skip the authority part
                // + 3 to skip the separator between protocol and authority
                if ((pos = curUrl.indexOf("/", pos + 3)) >= 0) {
                    // Trim everything after the authority part.
                    curUrl.setLength(pos);
                }
            }
            // Context path starts with a / if it is not blank
            curUrl.append(servletRequest.getContextPath());
            // Servlet path starts with a / if it is not blank
            curUrl.append(servletRequest.getServletPath());
            curUrl.append(theUrl, targetUri.length(), theUrl.length());
            return curUrl.toString();
        }
        return theUrl;
    }

    /**
     * The target URI as configured. Not null.
     */
    public String getTargetUri() {
        return targetUri;
    }

    /**
     * Closes this stream and releases any system resources associated
     * with it. If the stream is already closed then invoking this
     * method has no effect.
     *
     * <p> As noted in {@link AutoCloseable#close()}, cases where the
     * close may fail require careful attention. It is strongly advised
     * to relinquish the underlying resources and to internally
     * <em>mark</em> the {@code Closeable} as closed, prior to throwing
     * the {@code IOException}.
     *
     * @throws IOException if an I/O error occurs
     */
    //@Override
    public void close() throws IOException {
        destroy();
    }
}
